The present invention relates to the door closure arts. It finds particular application in connection with restraining a door across an opening to a steam sterilization chamber, and will be described with particular reference thereto. It should be appreciated, however, that the invention is also applicable to a wide variety of doors which are to be securely fastened to a pressure vessel or which are to be secured on four sides, such as vault doors or ship doors.
Conventionally, steam sterilizers are operated at high internal pressures and temperatures. To maintain these temperatures and pressures, the door of the sterilizer is generally clamped in position across an opening to the sterilization chamber by a closure assembly. Typically, a sterilization chamber door must be sealed to approximately 15 to 20 Kilograms force to prevent the door from leaking. A gasket or other flexible member is sealed between the door and the chamber. The closure assembly inhibits the ingress of air around the seal and also prevents hazards arising from accidental opening of the door during a sterilization cycle.
U.S. Pat. Nos. 4,756,123 and 4,891,910 disclose examples of closures for sealingly engaging a door across the opening to a sterilization chamber. U.S. Pat. No. 4,891,910 discloses a motorized closure assembly which drives a central locking wheel. A plurality of arms are connected to the locking wheel. The arms move upon rotation of the locking wheel until outer ends of the arms engage a plurality of apertures positioned along the perimeter of the opening to the chamber. Such closure assemblies are often complex, requiring a number of moving parts.
The present invention provides for a new and improved closure assembly for restraining a sterilizer door which overcomes the above-referenced problems and others.